Winding density is an important characteristic of a yarn package because it is indicative of the quality thereof. For instance, a yarn package having large fluctuations in the winding density during the winding process encounters significant problems during further processing such as dyeing and, particularly, unwinding.
Modern winding stations, particularly those in automatic winding machines, include devices for keeping the winding density of the randomly wound yarn package constant throughout most of the winding process. For example, it is known to compensate the contact force with which the yarn package rests on the friction roller driving it. It is also known to keep the yarn tension with which the yarn is wound onto the yarn package constant and, in particular, this method of maintaining a constant yarn tension results in a relatively uniform winding density.
Nevertheless, periods of increased winding density are encountered in spite of yarn tension maintenance and in spite of compensation of the contact force as a result of so-called pattern winding zones of the winding process. Moreover, increases in the winding density occur even when pattern disruption methods are employed, such as, for example, by alternatively accelerating the friction roller with slippage between the friction roller and the yarn package, and decelerating the friction roller without slippage between the friction roller and the yarn package. Hence, there remains a need for a method and an apparatus by which changes in the winding density resulting from pattern winding zones can be minimized.